The flow of history confirms the reality of the Gospel: the Church is filled to overflowing with sinners. Does their presence in the Church reduce, violate, or destroy her sanctity? Not in the least! For her Head—the Lord Christ, and her Soul—the Holy Spirit, and her divine teaching, her mysteries, and her virtues, are indissolubly and immutably holy. The Church tolerates sinners, shelters them, and instructs them, that they may be awakened and roused to repentance and spiritual recovery and transfiguration; but they do not hinder the Church from being holy. Only unrepentant sinners, persistent in evil and godless malice, are cut off from the Church either by the visible action of the theanthropic authority of the Church or by the invisible action of divine judgment, so that thus also the holiness of the Church may be preserved.
Whenever we enter the church and draw near to the heavenly mysteries, we ought to approach with all humility and fear, both because of the presence of the angelic powers and out of the reverence due to the sacred oblation; for as the Angels are said to have stood by the Lord's body when it lay in the tomb, so we must believe that they are present in the celebration of the Mysteries of His most sacred Body at the time of consecration.